/* ------------------------------------------------------------------- */
typedef struct ir_loop ir_loop;
-/* Loop elements are loop nodes and ir nodes */
+/** Loop elements: loop nodes and ir nodes */
typedef union {
firm_kind *kind; /**< is either k_ir_node or k_ir_loop */
ir_node *node; /**< Pointer to an ir_node element */
/** Set the outermost loop in ir graph as basic access to loop tree. */
void set_irg_loop(ir_graph *irg, ir_loop *l);
+
+/* Returns the root loop info (if exists) for an irg. */
ir_loop *get_irg_loop(ir_graph *irg);
/** Returns the loop n is contained in. NULL if node is in no loop. */
/* Sons are the inner loops contained in this loop. */
/** Returns the number of inner loops */
int get_loop_n_sons (ir_loop *loop);
+
+/** Returns the pos`th son loop (inner loop) of a loop.
+ Returns NULL if there is not a pos`th loop_node. */
ir_loop *get_loop_son (ir_loop *loop, int pos);
+
/** Returns the number of nodes contained in loop. */
int get_loop_n_nodes (ir_loop *loop);
+
+/** Returns the pos`th ir_node of a loop.
+ Returns NULL if there is not a pos`th ir_node. */
ir_node *get_loop_node (ir_loop *loop, int pos);
/** Returns the number of elements contained in loop. */
/* Constructing and destructing the loop/backedge information. */
/* ------------------------------------------------------------------- */
-/** Constructs backedge information for irg in intraprocedural view.
- * @returns Maximal depth of loop tree. */
+/** Constructs backedge information and loop tree for a graph in intraprocedural view.
+ *
+ * The algorithm views the program representation as a pure graph.
+ * It assumes that only block and phi nodes may be loop headers.
+ * The resulting loop tree is a possible visiting order for dataflow
+ * analysis.
+ *
+ * @returns Maximal depth of loop tree.
+ *
+ * @remark
+ * One assumes, the Phi nodes in a block with a backedge have backedges
+ * at the same positions as the block. This is not the case, as
+ * the scc algorithms does not respect the program semantics in this case.
+ * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
+ * nodes. They form a cycle. Once the scc algorithm deleted one of the
+ * edges, the cycle is removed. The second Phi node does not get a
+ * backedge!
+ */
/* @@@ Well, maybe construct_loop_information or analyze_loops ? */
int construct_backedges(ir_graph *irg);
-/** Constructs backedges for all irgs in interprocedural view. All
- loops in the graph will be marked as such, not only realizeable
- loops and recursions in the program. E.g., if the same funcion is
- called twice, there is a loop between the first function return and
- the second call.
- * @returns Maximal depth of loop tree. */
+/** Constructs backedges for all irgs in interprocedural view.
+ *
+ * @see As construct_backedges(), but for interprocedural view.
+ *
+ * @remark
+ * All loops in the graph will be marked as such, not only
+ * realizeable loops and recursions in the program. E.g., if the
+ * same funcion is called twice, there is a loop between the first
+ * function return and the second call.
+ *
+ * @returns Maximal depth of loop tree.
+*/
int construct_ip_backedges(void);
-/* Construct loop tree only for control flow.
+/** Construct loop tree only for control flow.
+ *
+ * This constructs loop information resembling the program structure.
+ * It is useful for loop optimizations and analyses, as, e.g., finding
+ * iteration variables or loop invariant code motion.
+ *
+ * This algorithm computes only back edge information for Block nodes, not
+ * for Phi nodes.
+ *
* @returns Maximal depth of loop tree. */
int construct_cf_backedges(ir_graph *irg);
+
+/** Construct interprocedural loop tree for control flow.
+ *
+ * @see construct_cf_backedges() and construct_ip_backedges().
+ */
int construct_ip_cf_backedges (void);
/** Removes all loop information.
- Resets all backedges */
+ * Resets all backedges. Works for any construction algorithm.
+ */
void free_loop_information(ir_graph *irg);
void free_all_loop_information (void);